(i) Technical Field
This invention relates to a fixing device and an image formation apparatus such as a copier and a printer using the fixing device.
(ii) Related Art
In an image formation apparatus of a copier, etc., a predetermined image formation process is adopted. For example, in the image formation process of an electrophotographic process, an electrostatic recording process, a magnetic recording process, etc., an unfixed image of objective image information (for example, toner image) is recorded and supported on a recording medium according to a transfer method or a direct method. As the recording medium, a transfer sheet, an electrofax sheet, electrostatic recording paper, an OHP sheet, print paper, and format paper can be named, for example. The unfixed image is heated and fixed on a recording medium side as a permanent fixed image in a fixing device.
As the fixing device, (a) a device adopting a heat roll method is widely used, but recently (b) a device adopting a film heating method has become commercially practical from the viewpoints of quick start and energy saving. (c) a device adopting an electromagnetic induction heating method has also become commercially practical.
In every fixing device described above, the recording medium takes heat at the fixing time, whereby the temperature of the portion through which the recording medium passes lowers. As the temperature lowers, it is feared that temperature unevenness at the fixing time may occur and a fixing failure of unevenness of image gloss, etc., may occur.